African wild mango (lrvingia gabonensis) is now recognized for its numerous food and medicinal uses. This plant produces seeds rich in fat, which is traditionally used as a soup thickener. in the present ... [more ▼]

African wild mango (lrvingia gabonensis) is now recognized for its numerous food and medicinal uses. This plant produces seeds rich in fat, which is traditionally used as a soup thickener. in the present study, the proximate composition of seeds from lrvingia gabonensis is reported. The oil from the seeds was then solvent extracted; its fatty acid (FA) and triacylglycerol (TG) profiles were determined. Besides this chemical characterization, the melting and crystallization behaviour of the extracted fat was studied by pNMR, DSC and X-ray diffraction. The result of this investigation showed that the seeds from lrvingia gabonensis (IG) represent an important source of lipids (69-75%), rich in myristic (49.8%) and lauric acid (37%). This fat can be classified among "lauric fats". IG oil presents a good oxidative stability due to its low content in unsaturated fatty acid. The melting profiles of IG oil indicates that a high amount of fat remains solid at temperatures up to 30°C; the complete melting was detected at around 40C. The most stable polymorph of this fat is the β'1 -form. [less ▲]

Plants belonging Dacryodes and lrvingia genus have great economic importance in Central and West Africa. lrvingia gabonensis (IG) produces a seed rich in fats, traditionally used as a soup thickener ... [more ▼]

Plants belonging Dacryodes and lrvingia genus have great economic importance in Central and West Africa. lrvingia gabonensis (IG) produces a seed rich in fats, traditionally used as a soup thickener. Fruit of Dacryodes edulis (DS) contains a pulp how are also rich in fat. Its seed constitute a big waste problem in towns and village remains not exploitable by local people however that may be valued as a resource for various components. Some study shows that this seed contented a proportion of oils that would be an alternative in the substitution of diesel relevant to their physicochemical properties. Despite the potential of two different oils, theirs scientific data still lack. In this work, thermo-physical behaviour of those two oils is compared in the aim to improving knowledge about properties of those oils that will promote their valorisation in industry scale. The result of this investigation showed that IGO have a highest proportion of oil content with 72.38% compared to DSO (14.64%). IGO is rich in myristic (49.8%) and lauric fatty acid (37%) but DSO sample was found to possess a higher proportion of linoleic acid (35.13%), palmitic (32.67%), oleic (17.70%) but lower proportion of stearic (9.97%). SFC of IGO was the highest at all temperatures. IGO is solid at room temperature with a complete melting at 40°C but DSO is liquid at room temperature. The polymorphism profile of IGO and DSO shows the 13' form stable during heating and a transition to liquid state without passage at β form. [less ▲]

The chemical characteristics of co-products recovered during a laboratory-scale wet milling procedure as well as that of whole corn flour were characterised and their digestibility and fermentability ... [more ▼]

The chemical characteristics of co-products recovered during a laboratory-scale wet milling procedure as well as that of whole corn flour were characterised and their digestibility and fermentability value determined using a 2 steps in vitro digestibility and fermentation model of the pig digestive tract. Five co-products differing in their chemical composition were collected and analysed. These co-products differed in their in vitro dry matter Digestibility and in their kinetic of fermentation. High coefficients of digestibility were observed for starchy samples, while low coefficients of digestibility were observed for samples rich in lignocellulosic components. Fermentation patterns of samples analysed were different as well as the profile of volatile fatty acids produced during the fermentation. The production of straight-chain fatty acids produced was significantly correlated with the proportion of starch in the sample, while branched-chain fatty acids were correlated to proteins concentration of samples. [less ▲]

In previous studies, Bacillus subtilis has been used to control mould growth during red sorghum malting. The use of this biocontrol in steeping liquor has been optimized with some success and the combined ... [more ▼]

In previous studies, Bacillus subtilis has been used to control mould growth during red sorghum malting. The use of this biocontrol in steeping liquor has been optimized with some success and the combined use of a 0.2% NaOH steep, followed by a resteep in a Bacillus subtilis-based biocontrol, has been proposed. The sharpness and variability of the β-amylase peak and the higher levels of β-glucanase obtained in the presence of B. subtilis cells were highlighted. In this work, the suitability of the Weibull 4 Parameters Model to predict sorghum malt α-amylase activity during the enzyme induction stage of red sorghum germination has been compared with those of a 2nd Order Polynomial Model and a General Linear Model. Results obtained showed that the Weibull 4 Parameters Model could be used to predict α-amylase activity, with significant goodness of fit when compared to the 2nd Order Polynomial Model and to the General Linear Model. The effects of steeping treatment (combined use of 0.2% NaOH and Bacillus subtilis S499 starters) and the germination temperature are presented. When the Bacillus subtilis culture used as a starter was diluted, the treatment efficacy to develop α-amylase activity was lost. This study also showed that the germination temperature affected the α-amylase activity rate increase during the induction phase. [less ▲]

Malting is the ideal stage to deal with β-glucans. Their hydrolysis is very important as the diffusion of both hormones and hydrolytic enzymes in the endosperm of germinated grain depend on it. A high ... [more ▼]

Malting is the ideal stage to deal with β-glucans. Their hydrolysis is very important as the diffusion of both hormones and hydrolytic enzymes in the endosperm of germinated grain depend on it. A high malt β-glucanase activity is not a guarantee of an extensive hydrolysis of β-glucans. When Bacillus subtilis is used to control mould growth, red sorghum malt β-glucanase activity (measured using carboxymethylcellulose as the substrate) was improved without significantly affecting the hydrolysis of malt β-glucans. Thus, in order to reduce the residual β-glucans content, soaking in 0.2% NaOH was combined with a biocontrol. Soaking in 0.2% NaOH is recognized as capable of improving grain hydration by opening-up the endosperm cell walls. The combined use of 0.2% NaOH with Bacillus subtilis-based biocontrol treatments during red sorghum malting, leads to malt with increased β-glucanase activity and a significant reduction of residual β-glucans when compared with the 16 h biocontrol steeping without prior steeping in 0.2% NaOH. β-glucanase activity increases with increased germination temperature and time while, conversely, the residual β-glucans content of the malts decreases. Indeed, while the level of β-glucanase was not vastly different between the malts obtained after steeping in distilled water and those obtained after 8 h steeping in 0.2% NaOH followed by 8 h resteeping in distilled water (NaOH+H2O treatment), their residual β-glucans levels differ significantly. Bacillus subtilis-based treatment leads to malt with improved β-(1-3)- and β-(1-4)-glucanase activities without significantly improved malt β-(1-3),(1-4)-glucanase activity. While malts obtained after 84 h germination weren’t significantly different in terms of malt β-(1-3),(1-4)-glucanase activities for all steeping treatments, the use of 0.2% NaOH steeping prior to resteeping led to malts with improved β-glucans content. Combining the steeping in dilute alkaline and biocontrol enables taking advantage of the dilute alkaline effect on residual β-glucans content, due probably to the opening-up the cell walls and the improvement of water uptake, and that of the biocontrol (improvement of β-glucanase synthesis). [less ▲]

Corn (Zea mays L.) is the most abundant cereal grain produced in the world. It also provides a significant amount of protein in human and animal diets. During drying corn grains undergo several ... [more ▼]

Corn (Zea mays L.) is the most abundant cereal grain produced in the world. It also provides a significant amount of protein in human and animal diets. During drying corn grains undergo several alterations including protein denaturation. A series of studies have been conducted in order to understand mechanisms behind denaturation of corn proteins during drying and heat moisture treatments. Using a laboratory fluidized-bed dryer, a flint corn variety have been dried between 54° and 130°C and subjected to different analyses from a qualitative point of view with a sequential extraction of corn protein fractions and from a quantitative point of view with the modeling of salt-soluble proteins using Promatest assay. Albumin, globulin and zein solubilities dropped significantly when the drying temperature increased. The electrophoretic patterns of zein and glutelin-G1 were not significantly modified, although the solubility of zein was affected by the drying temperature. The analysis of the different protein group solubilities suggested that denaturation mechanisms other than the creation of new disulfide bonds occurred during the drying of corn at high temperature. The study of the effect of heat treatments on the extractability of salt-soluble proteins shows that temperature; moisture content and time of processing greatly influence their kinetic denaturation. Modeling of salt-soluble proteins reveals that the evolution of extractible salt-soluble proteins content of corn kernels during drying at high temperature is more correctly described with a second order kinetic reaction. Investigations continue in order to understand protein denaturation and influence in functional properties and end-use of corn protein-based products. [less ▲]

The size of wheat starch granules was measured during isothermal and non-isothermal treatments and fitted using mathematical models in order to elucidate the time–temperatures dependence of the swelling ... [more ▼]

The size of wheat starch granules was measured during isothermal and non-isothermal treatments and fitted using mathematical models in order to elucidate the time–temperatures dependence of the swelling phenomenon and to improve our understanding of the mechanism followed by granules during gelatinization. Upon the onset temperature of gelatinization, starch granules size increase rapidly and tend to reach equilibrium values that depend on the temperature and heating rate applied. The most accurate fitting of granule size observed overall isothermal treatments was obtained with the third-order kinetic and the Weibull empirical models. The activation energy of swelling calculated for isothermal treatment varied between 41 and 318 kJ mol 1, depending on the mathematical model considered. Therefore, without a consensus on the mechanism and order of reaction followed during gelatinization, the meaningful of kinetic parameters calculated using mathematical models seems highly questionable. During non-isothermal treatments at lower heating rate, it seems like a limitation of the swelling capacity of granules was induced. This phenomenon was attributed to restructuration occurred inside of granules. So, forecasting the swelling behaviour of starch granules during non-isothermal treatment has to consider both the time–temperature and the heating rate applied. [less ▲]

With the globalization of the market, food industries need to adapt their processes to establish their presence in far away countries. Long transports are problematic for fresh food products as they ... [more ▼]

With the globalization of the market, food industries need to adapt their processes to establish their presence in far away countries. Long transports are problematic for fresh food products as they drastically reduce the already short shelf life. To counter this problem, the idea to freeze food for ransport and thaw it on arrival could be an alternative solution to propose an acceptable shelf life to the consumer. This brings new challenges as although freezing is thoroughly mastered, thawing is not. The main visible alteration of thawing is a water syneresis phenomenon leaving the product unfit for consumption. Indeed, water affects foods at several levels such as safety, stability, quality, and physical properties [1]. To investigate this problem, starch, a common polymer encountered in a wide variety of food, seemed to be a good model in gel form considering the three main food complexity dimensions which are: compositional, structural, and dynamical complexity [2, 3]. [less ▲]

In order to improve the hydrolysis of cellulose fiber and to obtain highly concentrated hydrolysate, two methods based on successive addition of enzyme and substrate were assessed. The first method, which ... [more ▼]

In order to improve the hydrolysis of cellulose fiber and to obtain highly concentrated hydrolysate, two methods based on successive addition of enzyme and substrate were assessed. The first method, which required only substrate addition, allowed to increase by 50% the hydrolysate concentration and to decrease by 30% enzyme units needed. The second method highlighted the ability to reach very high concentrated hydrolysate (up to 170 g/l) by simultaneous addition of enzyme and substrate. In parallel, relationships between some limiting factors and the yields of hydrolysis were investigated. In conclusion, viscosity evolution of cellulose suspension during hydrolysis step was investigated with an aim to improve the management of enzyme and substrate addition. [less ▲]

The effect of heat treatments (drying and hydrothermal treatment) on the extractability of salt-soluble protein (SSP) was assessed using Promatest methodology for corn kernels heated between 60 C and 120 ... [more ▼]

The effect of heat treatments (drying and hydrothermal treatment) on the extractability of salt-soluble protein (SSP) was assessed using Promatest methodology for corn kernels heated between 60 C and 120 C. During drying, the evolution of the grain moisture content is fitted using the analytical solution of Fick equation developed by Crank (1979) for spherical material. The decrease of extractible salt-soluble protein during heating is forecasted using a first and a second order ordinary differential equation. It was found that temperature; moisture content and time of processing greatly influence the kinetic denaturation of SSP of corn kernels. The evolution of extractible SSP content of corn kernels during drying at high temperature is more correctly described with second order kinetic than with the first order kinetic reaction. The Hunterlab color parameters of corn also vary during drying. Lightness and color intensity decrease while yellowness, redness, chroma and hue angle increase through drying time. Most of these Hunterlab color parameters are highly correlated with the salt-soluble proteins content and therefore could be used as indicators of excessive heat treatment and denaturation of salt-soluble proteins in corn kernels [less ▲]

In order to separate its major components, corn kernel is processed using the wet-milling process during which steeping, milling and starch/gluten separations appear to be the most important operations ... [more ▼]

In order to separate its major components, corn kernel is processed using the wet-milling process during which steeping, milling and starch/gluten separations appear to be the most important operations. To improve the efficiency of this process, corn wet-milling industry expended considerable resources focusing on improved process control, more efficient process equipment and on the development of hybrids that decrease the variability and reduce production costs. However, important variability is still observed according to the thermal history of grain after harvesting. The present article reviews up-to-date literature on the effect of drying conditions on the corn wet-milling performance and the physicochemical and functional properties of corn wet-milled fraction. Literature in this topic shows that high drying temperature combined with high initial moisture content of grain impact significantly the wet-milling performance and the quality of recovered materials. Further studies on the influence of drying process on the quality of starch, gluten, germ and fiber recovered during the wet-milling process are needed and would help to develop more accurate engineering and economic models for the corn wet milling process. [less ▲]

At harvest time, maize (Zea mays L.) has a moisture content too high to be stored, and has to be dried. To control the previous termdryingnext term impact on maize characteristics, it is necessary to ... [more ▼]

At harvest time, maize (Zea mays L.) has a moisture content too high to be stored, and has to be dried. To control the previous termdryingnext term impact on maize characteristics, it is necessary to accurately know the spatial distribution of temperature and moisture content in the kernel, and the kinetics of quality loss in relation to these two factors. To this end, a physical model of heat and mass transfer in a maize kernel was designed. The Fick and Fourier equations were solved by the finite element method (FEM). The real 3D geometry of maize was obtained by NMR imaging and then used to build the mesh needed for the FEM computations. The model correctly describes the evolutions of maize moisture and salt-soluble protein content during fluidized-bed previous termdryingnext term with a constant previous termdryingnext term air temperature between 50 °C and 100 °C. [less ▲]

This manuscript compares the modifications induced by the heat-moisture treatment of native starch (HMT) and by the hot-air drying of corn on wet-milled starch granules. High temperatures applied during ... [more ▼]

This manuscript compares the modifications induced by the heat-moisture treatment of native starch (HMT) and by the hot-air drying of corn on wet-milled starch granules. High temperatures applied during both corn drying and HMT reduced the swelling capacity of granules, increased the starch gelatinization temperatures and decreased their residual enthalpy. Pasting behaviour of pre-treated starch showed a decrease of peak and breakdown viscosity when corn drying and HMT temperatures increased. Microscopic analysis showed that after hydrothermal treatment, starch granules extracted from corn dried at lower temperature swell more significantly than those extracted from corn dried at higher temperature. All these changes suggest the occurring of structural modifications within starch granules during high-temperature pre-treatments. At similar temperatures and initial moisture contents, HMT affected the physicochemical and functional properties of cornstarch more dramatically than hot-air drying. Differences induced by these two treatments were attributed to the availability of water around granules during these two pre-treatment procedures. [less ▲]